Community Forums

sueb77 · 01-19-2022, 06:51 AM

I have a Mercedes chassis with infotainment center. The RV has outside speakers. While parked and plugged into shore power, the radio shuts off after 30 minutes. I read somewhere that the stereo is on a timer. Has anyone figured out how to use the stereo for a longer time? After all, why would there be outside speakers?

luvlabs · 01-19-2022, 08:47 AM

Your outside speakers are not part of the chassis radio system. Look around for the sound system that operates with your TV. Normally these contain a radio and DVD player and can be connected to the outside speakers.

Knittler · 01-19-2022, 03:19 PM

After you turn off your Sprinter and exit the driver door, reach back in and turn the entertainment system back on by pressing on/off button to lower right of the screen .

sueb77 · 01-23-2022, 02:33 AM

The outside speakers are definitely part of the Mercedes MBUX infotainment unit. It plays the radio (or bluetooth, sirius, etc) to the outside speakers when switch inside the coach is turned on (located by the step with other switches). I've used it in this manner, but only for 1/2 hour when the RV is shut off and plugged into shore power.

RonandDeb · 01-25-2022, 06:55 PM

I also have a 2020 Qwest and noticed the same thing. There is a switch inside the door which allows either the inside or outside speakers to play and only work with the chassis head unit.

Certainly doesn't make sense, however, you're not alone!! If I find anything out, I'll let you know. Please do the same

sueb77 · 01-26-2022, 05:44 AM

Thank you for your reply. I recently learned that you cannot stayed plugged into shore power for any length of time without running the engine. My starting battery had discharged and would not start without jumping from the house batteries. I am going to buy a small trickle-charger to use next time. I will get a small one that will fit under the hood and plug it into the outlet inside the passenger side outside compartment, or plug it into the power post at campground. I will be curious to see if the stereo/infotainment system will stay running longer than 1/2 hour if the battery stays fully charged.??

DAJO · 01-26-2022, 08:05 AM

If you look at your owners manual it tells you how to disconnect the battery while parked on in storage. The disconnect is beside your right leg below the knee.

TexasSprinter · 02-01-2022, 06:30 PM

I've noticed the exact same thing. The chassis radio is connected to both the outdoor speakers and the coach indoor (rear) speakers, but what good is that if you can't switch the system over to run from the house batteries? It makes no sense! I've asked the dealer about this and gotten nowhere at all. We carry portable speakers and use our phone and bluetooth, but it would make much more sense to use the built-in system.

If anyone has a way to get an answer from Entegra and/or a way to switch the system over to house batteries, I'd love to hear it!

azfrankp · 05-09-2023, 12:59 PM

I realize this thread is over a year old but here is some information I found for all you Sprinter chassis owners concerning the Radio Auto Off scenario. I have also attached a simple circuit work around that only costs around $10. First, here are some facts:

Yes, the head unit shuts off after a few minutes by design. Mercedes doesn't know how, or where, the chassis will end up. The reason for the auto off is to preserve battery power. This is an undesirable feature in an RV for obvious reasons.

The Internal and External speakers all work with the MBUX.

The batteries are charging while you are plugged in or operating with the generator.

Some RV Manufactures that use this chassis incorporate a bypass. Entegra does not.

There is a module that sells for almost $500 that allows you to bypass this feature. It is a little easier to install than my circuit. However, it is still undesirable because, if you forget to turn it off, it will keep the head unit on indefinitely and therefore drain the battery.

Having said that, no matter what you do, be aware that the MBUX unit requires a lot of power and could deplete the battery faster than you might think.

I have come up with a simple bypass circuit that allows the head unit to be on as long as you're running on external power or the generator. It may be easily adaptable to run on the coach batteries when dry camping but that's up to you if you're willing to risk the power draw. The theoretical power draw of the MBUX unit is approximately 100 watts on average and depends on the volume and other accessed features. 120 watts equates to about 10 Amps per hour, so the math states that an average new coach battery will last about 15 hours of constant use without anything else drawing from it.

The circuit diagram is attached. The only parts you'll need is a 120V AC SPDT relay with contacts rated for at least 15 amps, a 15A fuse and holder, and some wire, and splicing connectors. The theory behind this circuit is simple. Under normal running conditions, standby and storage conditions, the relay is not energized, and everything will work normally. When the RV is plugged in to external power, or the generator is started, the relay energizes and supplies the MBUX with 12 VDC to the ignition input which will keep it on until either is turned off. Installation is fairly simple. You'll need to access the coaches 12 volt power, the coaches 120 VAC power and locate the Ignition input to the MBUX. This is easily accessed from the control module in the engine compartment. The hardest part is getting that wire to the location where the module will be installed in the coach. I have mine in the storage location behind the TV where everything else is available.

To bypass without consideration for battery draw, You don't need the relay.
Simply replace it with a SPDT Toggle switch in place of the relay contact circuit.

You may PM me for questions or help.

Thanks,
Frank